In the printing field, the impact type printer has been the predominant apparatus for providing increased thruput of printed information. The impact printers have included the dot matrix type wherein individual print wires are driven from a home position to a printing position by individual and separate drivers, and the full character type wherein individual type elements are caused to be driven against a ribbon and paper or like record media adjacent and in contact with a platen.
The typical and well-known arrangement in a printing operation provides for transfer of a portion of the ink from the ribbon to result in a mark or image on the paper. Another arrangement includes the use of carbonless paper wherein the impact from a print wire or a type element causes rupture of encapsulated material for marking the paper. Also known are printing inks which contain magnetic particles wherein certain of the particles are transferred to the record media for encoding characters in manner and fashion so as to be machine-readable in a subsequent operation. One of the known encoding systems is MICR (magnetic ink character recognition) utilizing the manner of operation as just mentioned.
While the impact printing method has dominated the industry, one disadvantage of this type printing is the noise level which is attained during printing operation. Many efforts have been made to reduce the high noise levels by use of sound absorbing or cushioning materials or by isolating the printing apparatus. More recently, the advent of thermal printing which effectively and significantly reduces the noise levels has brought about the requirement for heating of extremely precise areas of the record media by use of relatively high currents. The intense heating of the localized areas causes transfer of ink from a ribbon onto the paper or alternatively, the paper may be of the thermal type which includes materials which are responsive to the generated heat.
Further, it is seen that the use of thermal printing is adaptable for MICR encoding of documents wherein magnetic particles are caused to be transferred onto the documents for machine reading of the characters. The thermal transfer printing approach for use in MICR encoding of documents enables reliability in operation at the lower noise levels.
Representative documentation in the area of magnetic ink for use in non-impact printing includes UK patent application No. 2106038A, published Apr. 7, 1983, which discloses a heat-sensitive magnetic transfer element for printing a magnetic image to be recognized by a magnetic ink character reader and which element comprises a heat-resisting foundation and a heat-sensitive transfer layer including a magnetic powder in a wax or plastic binder and having a melting point of 50 degrees to 120 degrees C. so that portions of the layer can be transferred onto a receiving paper in the form of a magnetic image by a thermal printer.
U.S. Pat. No. 3,042,616, issued to R. J. Brown on July 3, 1962, discloses a process of preparing magnetic ink by wetting powdered iron with a resinous solution and adding an aqueous slurry of carbonate to form droplets surrounded by solvent liquid. The solvent is separated by water and the particles are then filtered and dried to produce spheres of magnetic ink.
U.S. Pat. No. 3,117,018, issued to E. Strauss on Jan. 7, 1964, discloses a color transfer medium and method of producing the same by applying a coating consisting of a polycarbonate, a solvent, a plasticizer and a pigment, and then drying the coating to form a solid transfer layer.
U.S. Pat. No. 3,413,183, issued to H. T. Findlay et al. on Nov. 26, 1968, discloses a transfer medium provided by a coating process wherein the transfer layer is a polycarbonate having voids which hold an imaging material.
U.S. Pat. No. 3,744,611, issued to L. Montanari et al. on July 10, 1973, discloses an electrothermal printer for non-impact printing on plain paper that uses a ribbon made of a substrate having a thermal-transferable ink coated on one surface thereof and a coating of electrically resistive material on the other surface.
U.S. Pat. No. 3,855,448, issued to T. Hanagata et al. on Dec. 17, 1974, discloses a print ribbon comprising a heat-resistant support sheet with a heat-fusible material layer of thermoplastic resin, carbon black, pigment or oleic acid fats, and wax, mineral oils or vegetable oils.
U.S. Pat. No. 4,022,936, issued to R. E. Miller et al. on May 10, 1977, discloses a process for making a sensitized record sheet by providing a substrate, coating the substrate with an aqueous composition, and then drying the coating.
U.S. Pat. No. 4,103,066, issued to G. F. Brooks et al. on July 25, 1978, discloses a ribbon for non-impact printing comprising a transfer coating and a substrate which is a polycarbonate resin containing a percentage by weight of electrically-conductive carbon black.
U.S. Pat. No. 4,251,276, issued to W. I. Ferree et al. on Feb. 17, 1981, discloses a transfer ribbon having a substrate coated with a thermally-activated ink composition comprising a thermally-stable polymer, an oil-gelling agent, and an oil dissolving medium present in a percentage by weight of the total nonvolatile components.
U.S. Pat. No. 4,291,994, issued to T. L. Smith et al. on Sept. 29, 1981, discloses a ribbon for non-impact printing which comprises a transfer coating and a substrate containing resin which is a mixture of polycarbonate, a block copolymer of bisphenol carbonate and dimethyl siloxane, and a percentage by weight of electrically conductive carbon black.
And, U.S. Pat. No. 4,309,117, issued to L. S. Chang et al. on Jan. 5, 1982, discloses a ribbon configuration for resistive ribbon thermal transfer printing comprising a low resistive layer of conductive carbon, a high resistive layer of a ceramic metal mixture, a stainless steel conductive layer, and an ink transfer layer.